Kevin Lisbie, on loan at Colchester from Town, scored a brace on his return to the U's to set the Essex side on their way to an astonishing 5-0 half-time lead at Carrow Road.
And although the Canaries improved after the break it couldn't prevent a demoralising defeat for Bryan Gunn's side in their first match at this level since 1960.
An entertaining affair at Roots Hall ended 2-2 between Southend and Huddersfield, with former Town striker Jordan Rhodes netting the equalising goal for the visitors after making his debut from the subs bench.
Rhodes was not the only former Town player on target, with Dean Bowditch proving an instant hero for Yeovil as he grabbed the opening goal in a 2-0 win against Tranmere Rovers.
Elsewhere among other former Blues in action this afternoon, Kelvin Davis saved a penalty for Southampton in their league one clash against Millwall which finished 1-1, whilst an Alan Lee strike secured a point for Crystal Palace against Plymouth in the Championship.